1. Field of the Invention
The present invention relates to a propelling cage sabot, i.e., a discarding sabot, for spin-stabilized subcaliber multipurpose projectiles with the cage being made, at least in part, of shaped polyamide-containing plastic material. 2. Description of the Related Art
A propelling cage discarding sabot for spin stabilized subcaliber multipurpose projectiles is disclosed, for example, in EP-A 0,051,375 and in EP-A 0,146,745, the disclosures of which are herein incorporated by reference, and is shown in respective FIG. 1s. Such FAPDS projectiles, i.e., frangible armor piercing discarding sabot projectiles, are usually composed of tungsten heavy metal and are intended for use against, for example, combat aircraft, armored combat helicopters and fast moving, light-armor land targets. These projectiles are fired at high cadences, i.e., about 400 to 800 rounds per minute, from automatic weapons having a caliber of, for example, 20 to 35 mm.
The sabot of such discarding sabot projectiles should have minimal dead weight, i.e., the sabot should weigh as little as possible. Moreover, the ammunition should be economical and ensure a high hitting accuracy. Ammunition for automatic weapons is known to be subject to high loading stresses since it is introduced into the weapon at high speed and is suddenly braked in the cartridge chamber. Prior art ammunition employing discarding sabot components made of polyamide-containing plastic materials has been found to absorb substantial amounts of water and, thus, swell so that the ammunition does not retain its intended dimensions. Such ammunition increases in diameter, i.e., in its caliber, so that it can be loaded into a weapon only with a very great amount of force, if it can be loaded at all, and is difficult to unload or cannot be unloaded as a practical matter. Additionally, and quite predictably, weapon malfunctions are the immediate result of such an expansion of the propelling cage discarding sabot components, particularly hood elements thereof.
The increase in caliber due to irregular diameter dimensions upon absorption of water makes attaining constant internal ballistics impossible. Great fluctuations in initial velocity V.sub.o due to, for example, different amounts of friction in the gun barrel, yield poor hit results under continuous firing.
The swelling of the plastic sabot may additionally lead to a considerable enlargement of the inner bore thereof, which functions as a projectile receptacle, in the axial and radial directions so that the projectile sits loosely within the sabot. Thus, when fired, a heavy pendulum action produces undue interference as the projectile passes through the gun barrel and results in poor hitting accuracy.
If the mechanical properties, e.g., elasticity, change due to the absorption of water, irregular release behavior of the discarding sabot segments occurs with increasing frequency. Absorption of water, for example, makes prior art plastic materials tougher and/or irregularly more elastic so that the sabot component parts, in particular hood segments of the hood thereof, take longer to tear apart after they leave the gun muzzle and tearing becomes more irregular. Thus, interference with the trajectory of the projectile body after firing becomes more serious and more frequent.